I74 ' PRACTICAL ORGANIC CHEMISTRY
" sodium nitrite is gradually added, the temperature being kept
below ioc, until a drop of the mixture, diluted with water, turns
potassium iodide-starch paper blue. To the mixture, still cooled
in ice, 120 grams stannous chloride, dissolved in about an
equal weight of cone, hydrochloric acid, is added. A thick
white crystalline precipitate of phenylhydrazine hydrochloride
separates. It is allowed to stand for half an hour and filtered at
the pump ; it is then separated as far as possible from the mother
liquor, and transferred to a flask. The free base is obtained by
decomposing the hydrochloride with caustic socla. An excess
of caustic soda is added, and the mixture well shaken. The
free base, which separates as a reddish coloured oil, is extracted
with ether, and the ethereal solution dehydrated over solid
potassium carbonate. The ether is then removed on the water-
bath, and the residual oil either used without further purification
or distilled in vacua. Yield, 1 5 — 20 grams.
C0H5N H2. H Cl 4- NaN O2 + H Cl = CGH5N,. Cl +
Properties. — Nearly .colourless oil when freshly distilled ;
b. p. 241—242° ; m. p. 17-5° ; sp. gr. 1-097 at 23°.
Reactions. — i. Add a few drops of phenylhydrazine to 2 c.c.
of water, then a drop or two of copper sulphate solution and
excess of caustic soda. Cuprous oxide is precipitated with
effervescence and benzene separates, C0HsNH.NH2 + 2CuO —
C6H0+N2+Cu2O + H2O. The same reaction takes place if
the phenylhydrazine is dissolved in dilute acetic acid and copper
sulphafte solution added and warmed.
2. Add 2 grams of phenylhydrazine to 4 c.c. water in a boiling-
tube, warm until dissolved, and then add about 3 c.c. of a warm
saturated solution of cupric hydrate dissolved in cone, ammonia.
Nitrogen is evolved and cuprous hydroxide dissolves. Add a 10
per cent, caustic potash solution until there is a slight permanent
precipitate of cuprous hydroxide and heat the liquid in the
water-bath. A copper mirror is .deposited on the surface of the
3. Add to a few drops of phenylhydrazine an equal quantity
of glacial acetic acid, dilute with a little water, and a1:ld a